The present invention relates to a novel class of compounds which have structures related to certain naturally occurring and synthetic chalcones, as well as to methods for the preparation of such compounds and to pharmaceutical uses thereof.
The compound 1,3-diphenyl-2-propene-1-one is known by the trivial name xe2x80x9cchalconexe2x80x9d. Many naturally occurring flavonoids share structural features with chalcone and are referred to by the generic term xe2x80x9cchalconesxe2x80x9d. Also, certain flavonoids, including ones which are also classified as chalcones, have recently been demonstrated to have anticancer activity (Cancer Research, 48, 5754, 1988) and chemopreventive activity in some tumours (J. Nat. Prod., 53, 23, 1990).
In particular, quercetin, an ubiquitous flavonoid found in plants, has been shown to act on the proliferation of human leukemic cells (Br. J. of Haematology, 75, 489, 1990) and on other cell lines (Br. J. Cancer, 62 94, 942, 1990; Int. J. Cancer, 46, 112, 1990; Gynecologic Oncology, 45, 13, 1992) and to possess a synergistic action with common antiblastic drugs.
In addition, some natural or synthetic chalcones, described in our International Patent Publication No. WO 91/17749 and in International Patent Publication No. WO 96/19209 (Baylor College of Medicine) have proved to have a significant antiproliferation activity on a variety of different cell lines.
Although the mechanism of action of the antiproliferation activity of flavonoids and chalcones is still unknown, it is believed to be linked to the interaction of these compounds with type II estrogen receptors.
The action in vivo of these polyphenol substances is certainly much more complicated. All these compounds are generally characterized by an almost complete insolubility in water and, in vivo, by a very poor bioavailability linked to a rapid metabolism of phenols and a marked affinity for lipids and proteins.
Surprisingly, it has now been found that certain novel chalcones, chalcone derivatives and chalcone analogues, in particular ones in which the phenyl ring in the 3-position is substituted or replaced by rings containing one or more heteroatoms, possess a greater antiproliferation activity both on sensitive cancerous cells and on cells which are resistant to common chemotherapeutic drugs, including the latest generation anti-neoplastic agents, paclitaxel and docetaxel.
Thus according to one aspect of the present invention, there are provided compounds of the general formula (A) 
wherein:
Ar represents phenyl, which may be unsubstituted or substituted by one, two or three substituents independently selected from Cl, Br, F, xe2x80x94OMe, NO2, CF3, CN, C1-4 lower alkyl (preferably methyl), xe2x80x94NMe2, xe2x80x94NEt2, xe2x80x94SCH3, xe2x80x94NHCOCH3; 2-thienyl; 2-furyl; 3-pyridyl; 4-pyridyl or 3-indolyl; and R represents xe2x80x94OCH2R1, in which R1 is selected from xe2x80x94CHxe2x95x90CMe2, xe2x80x94CMexe2x95x90CH2, or xe2x80x94Cxe2x89xa1CH; with the proviso that where Ar represents phenyl, R is other than 3-methyl-2-butenyloxy.
Within this class, preferably Ar is selected from unsubstituted phenyl, 3-pyridyl, 4-pyridyl and 3-indolyl. Particularly preferred are compounds wherein R represents xe2x80x94OCH2xe2x80x94CHxe2x95x90CMe2, xe2x80x94OCH2xe2x80x94CMexe2x95x90CH2, or xe2x80x94OCH2xe2x80x94Cxe2x89xa1CH.
Compounds of formula (A) which contain a basic amino function may be converted to acid addition salts with pharmaceutically acceptable acids such as hydrochloric and phosphoric acids and such salts are included in the present invention.
This invention also includes the use of the compounds of Formula (A) in the treatment and prevention of neoplasms, particularly of the uterus, ovary and breast, and in the treatment and prevention of menopausal disorders and osteoporosis. The invention further includes pharmaceutical compositions comprising one or more of the compounds of Formula (A) and one or more pharmaceutically acceptable excipients.
In vitro results have shown that the compound of the invention have a marked affinity to type II estrogen receptors and are inhibitors of tyrosine kinase. Further they are capable of inhibiting the activity of the P-170 protein pump that mediates the MDR in tumoral cells, and of antagonizing the proliferation of both hormone-dependent and chemoresistant tumoral cells in the same proportion.
The mechanisms of action of the compounds of Formula (A) are most probably different from the those of structurally related prior art compounds, (including natural occurring chalcones) inasmuch as they can completely inhibit protein P-170. For these reasons, the compounds of the invention show a more marked activity, both in vitro and in vivo, than other products known in the prior art.
The affinity of some compounds for type II receptors and the antiproliferative activity on ovarian tumoral cells are shown in Table 1.
The binding to type II estrogen receptors was evaluated in ovarian tumor cells and tumor cells of other target organs. The cells were grown in a single layer according to the known techniques reported in the literature. To make the test reproducibility, the cells were trypsin treated, every week and placed on plates at a density of 8xc3x97104 cells/cm2 and incubated at 37xc2x0 C. in air containing 5% CO2.
The various compounds under test, dissolved in ethyl alcohol, were added at serial dilutions and the treated cells and control cells were incubated with 3H-estradiol or in the presence of diethylstilbestrol according to the methods described by literature. The antiproliferation activity were verified in the same way by adding the compounds, dissolved in DMSO, to the medium and performing a cell count after 72 hours.
The compounds according to this invention inhibit the cell proliferation in vivo as can be demonstrated by examining the size of the tumours implanted in athymic naked mice according to the techniques that are extensively reported in literature.
Treatment of animals with doses ranging from 1 mg/kg to 200 mg/kg produced a marked reduction in size of the tumours with the total retrogression of the tumour in many of the animals treated.
The compounds according to the invention can suitably be administered enterally or parenterally (e.g. orally or by injection) in pharmaceutically acceptable vehicles. The dosage for treatment and prevention of neoplasms with the compounds of the invention (which are essentially non-toxic) can vary from 50 mg to 1,000 mg per day for a time ranging from a month to several years depending on the nature and severity of the disease.
The compounds of the invention are especially useful in combination therapies along with other anti-neoplastic drugs and/or physical anti-cancer treatments such as radiotherapy. Thus, for example, they can advantageously be administered in anti-tumour therapy prior to treatment with antiblastic drugs, so that the dosage of the latter and, consequently, their unwanted side effects, can be reduced to the patient""s advantage.
Given their clear antiproliferation activity on hormone-dependent tumoral cells and the activity on protein kinase, treatment of patients can be continued after the traditional chemotherapy or surgical operation for the removal of the tumour in order to block metastatic diffusion. The same compounds according to this invention can be used in prophylactic treatment for the prevention of tumours in the uterus, ovary and breast, as well as for the reduction of typical menopausal disorders.
In such cases the dosage may range from 5 mg/kg up to 100 mg/kg per day and furthermore the products may advantageously be administered orally in formulations containing phospholipids which facilitate their resorption.
The compounds according to the invention can be synthesized in two main ways:
a) by the reaction between an equimolar solution of acetophenone and an appropriate aldehyde in ethyl alcohol in the presence of KOH; and
b) by reacting an equimolar solution of acetophenone and an appropriate aldehyde in ethyl alcohol in the presence of piperidine and acetic acid under weak countercurrent.
At the end of the reaction, the products may crystallized from alcoholic solution or purified by means of chromatography. The reaction products generally have a high degree of purity, so that crystallization is usually sufficient to obtain the desired products in a high degree of purity.